In recorded interviews with PSNI detectives, Black was questioned about the 1981 murder of the Northern Ireland child.

In one haunting exchange he tells police: "I'm not exactly proud of the way I feel towards young girls."

"There's a part of me that knows I'm wrong, that knows it's wrong, that I shouldn't be doing things like that, I shouldn't even be thinking things like that.

"But there's the other part that says 'you like it, go on'."

The recordings were obtained by the BBC as part of a Spotlight one-hour special report into the life of the child killer will be shown tonight.

Following Black's death in an interview with the Belfast Telegraph Jennifer's mum, Pat Cardy, said she believed that Black took pleasure from witnessing their distress as his taped interviews were played to the court.

The Cardys had to wait 30 years before they came face-to-face in an Armagh courtroom with the man who had snatched their daughter as she cycled from their home to a friend's house on August 12, 1981.

"That was a terrible ordeal," she added. "He saw my face, he saw Andrew's face, he watched me giving testimony. How he sat there, how he looked, how blasé he became in front of you. Maybe as a woman I felt a particular kind of connection with things... I just had an instinct about him... and I saw a man who knew Jennifer, who remembered explicitly when he had been with her and what he had done to her. I saw a man who relished his memories. When the murders in England, for which he'd been convicted, were disclosed again at the trial, he relished that.

"He wanted to hold his personal memories of what he had done so that if and when he went to bed that night he would enjoy it. I saw that in him."

She also believed that he took pleasure from witnessing her own distress, particularly on one occasion when she fled the courtroom in tears: "They were playing tapes of his interrogation and the details were gruesome. He saw me walk out and I know that pleased him.

"He would have thought that he was the only one who that could do that to me, who had that power."

Black was a delivery driver who stalked the roads of the UK searching for victims.

In 1994, he was found guilty of three child murders in the 1980s - those of 11-year-old Susan Maxwell, from the Scottish Borders, five-year-old Caroline Hogg, from Edinburgh, and Sarah Harper, 10, from Morley, near Leeds - as well as a failed abduction bid in Nottingham in 1988.

In 2011, he was found guilty of the 1981 murder of nine-year-old Jennifer Cardy, from Ballinderry, Co Antrim.

He was also suspected of involvement in other killings and unexplained disappearances.

He had long been the prime suspect in the case of missing 13-year-old Genette Tate, who was last seen in a rural lane in Aylesbeare, Devon, in 1978.

The Belfast Telegraph revealed last month that he had been cremated after hours at Roselawn Crematorium on the outskirts of Belfast. His ashes were later discarded at sea after no one came forward to claim them.

No ceremony was held during the scattering at a secret location outside the UK.